PCT Patent Applications PCT/US2010/058810 and PCT/US2012/067812, assigned to the present assignee, describe devices for fracturing calcifications in heart valves. The device includes a catheter that has an expandable stabilizer, an impactor shaft and an internal shaft, all disposed in an external shaft. Expandable impactor arms are mounted on the impactor shaft. The internal shaft is movable to cause the impactor arms to expand outwards and be locked in an expanded shape. An impacting element is movable to cause the impactor arms, while in the expanded shape, to move towards the tissue with sufficient energy so as to fracture a calcification located in tissue which is fixed by the stabilizer in a certain position vis-à-vis the impactor arms. The internal shaft may be lockable relative to the impactor shaft so that the impactor arms are fixed.
A brief description of using the device is as follows. The catheter may be delivered over a guide-wire through a blood vessel, such as the peripheral artery, using a retrograde approach, through the aortic arch and into the ascending aorta, just above the aortic valve. The external shaft is retracted so that the expandable stabilizer expands and opens up. The stabilizer is used to guide, position and anchor the catheter distal part in the sinuses, just above the valve leaflets. An impactor shaft, including folded impactor arms, is then pushed forward (distally) through the center of the valve into the left ventricle. When pushed forward the impactor arms are folded so that they can easily cross the valve. The internal shaft is then pulled proximally to cause the impactor arms to open (expand) outwards sideways and lock them in the expanded shape. The impactor and internal shafts are manipulated so that the leaflets are “sandwiched” between the stabilizer (which may make contact with the leaflets from the aortic aspect) and the impactor arms (which may make contact with the leaflets from the ventricular aspect, or vice versa). In order to fracture leaflet calcifications, the impactor arms are pulled abruptly towards the leaflet tissue to impact the calcification, with the stabilizer serving as an anvil.
In one embodiment, the impactor has struts in a Y-shape (separated from each other at about 120°) and/or other struts which can be used in various rotational positions on the valve, such as on the ventricular aspect of the commissures or the centerline of the valve's leaflets. The structure of the impactor enables active self-positioning of the device on the aortic valve. For example, proximal structural struts are located higher than and at an angle relative to the impaction struts, so that the proximal structural struts position themselves just below the commissures when the impactor is pulled towards the valve.
The impaction struts and stabilizer are shaped in accordance with a shape of the desired fracture site, e.g., leaflet bases (close to the annulus) and central folding lines of the native valve. Accordingly, the shapes of the impaction struts and of the stabilizer may include portions with a bicuspid shape, a tricuspid shape, or a semilunar shape, and may additionally have a portion with a depression corresponding to the folding lines, depending on the valve to be treated. Due to these predetermined shapes, the impactor, by impacting against the stabilizer, is able to generate fractures along the leaflet bases (close to the annulus) and central folding lines of the valve.
The various impactor designs may be used to increase the open cross-sectional area of the valve during systole. In this method the impactor is inserted in a fully or partially closed configuration through the valve in between the valve's leaflets and then is gradually dilated to increase the open cross-sectional area of the valve. This method may be used before or after impact has been delivered to the leaflets to increase the effect of valve fractures on leaflet pliability, or without delivering impact to the valve. Impactor dilation of the valve may enlarge present fractures, create new fractures, stretch the valve and its immediate surroundings, separate fused commissures and soften calcific deposits within the valve.
The system can make pressure measurements from the ventricular and aortic aspects of the aortic valve.